Russia has vetoed a U.S. proposal in the United Nations Security Council to renew the mandate of a UN investigative team charged with determining who is responsible for chemical-weapons attacks in Syria.

The November 16 veto came hours before the UN Joint Investigative Mechanism was due to expire at midnight. It was Moscow's 10th such veto of UN resolutions involving the Syrian civil war since the conflict began in 2011.

The U.S. ambassador to the UN Nikki Haley said the veto showed Russia consistently puts protection of its ally Syria, which has been blamed for all but one chemical attack since the investigation started in 2015, above the protection of Syrian civilians killed in such attacks.

"Russia has killed the investigative mechanism, which has the overwhelming support of this council," she said. Eleven of the council's 15 members supported the U.S.-drafted resolution, which would have extended the investigation for another year.

"To my Russian friends, the next chemical-weapons attack is on your head," Haley said. "You are basically telling the entire world that chemical weapons are OK to use. That's what we should be embarrassed about today."

France's UN Ambassador Francois Delattre said the Russian veto was a blow to international efforts to curb the use of chemical weapons.

"Let there be no doubt: We have unleashed a monster here," said Delattre.

Russian UN Ambassador Vasily Nebenzya shot back, saying the investigative mechanism needed an overhaul, including a mandate to secure evidence of chemical use first-hand rather than through parties involved in the conflict.

Nebenzya called the mechanism "a puppetlike structure" that he said can be manipulated by the West. On the basis of false information, it will time after time accuse the Syrian government of violating international norms," he said.

Russia has been highly critical of the team's findings that the Syrian government used chlorine gas in at least two attacks in 2014 and 2015 and used sarin in an aerial attack on Khan Sheikhun last April that killed nearly 100 people.

Syria has repeatedly denied using chemical weapons. The investigative team also found the extremist group Islamic State was responsible for a mustard gas attack in 2015.

After Russia vetoed the U.S. extension proposal, the council later voted against a rival resolution put forward by Russia to overhaul the investigative mechanism. It received only four votes in favor -- from Russia, Kazakhstan, Bolivia, and China -- short of the nine votes needed to pass.

After the council votes, Japan circulated a draft resolution to extend the inquiry for an additonal month to provide time to negotiate a possible compromise, diplomats said.

It was not clear when or whether the council would vote on the temporary measure.

In the absence of further action, the investigative mechanism was due to expire at midnight on November 16.

U.S. President Donald Trump had urged the council to support the investigation's continued work. In a Twitter message shortly before the vote, Trump said this would "ensure" that President Bashar al-Assad's Syrian "regime does not commit mass murder with chemical weapons ever again."